Client Allows Game Start Without LoL Fully Installed

My computer crashed recently due to some issue with the Windows 10 Anniversary Update and I was forced to do a reset, wiping installed apps. After rebooting post reset, LoL was still installed and the icon on my desktop still brought up the game client. I was able to log in and even get through champ select in a game. Before the load screen loaded though, I got an error about a missing .dll file and had to abandon the game, resulting in a Leaver Buster warning. Not really complaining about the penalty, since from the other players' perspective I did leave.

Moral of the story though, this missing .dll should have prevented my actions before getting to the game load screen.